Your answer (B) is not the
one that we were looking for! (E) is correct!

It
is true that the patient's clinical picture and positive
blood cultures are consistent with bacterial endocarditis,
and that the right atrial mass could easily represent
a large vegetation. However, the homogenous and "soft"
echogenic appearance, filamentous projects and varying
contour are more in keeping with a large right atrial
thrombus in this patient with chronic atrial fibrillation.
An underlying vegetation probably served as a nidus
for the thrombus but is not felt to account for the
entire mass.

All the other options listed
in the question are true.You may review
the previous question again, if you so desire, by clicking on the left
corner prior key.